FAB1A/B overexpressing plants become dwarfed and sterile dose dependently. A, Expression levels of four independent lines of FAB1A with different expression levels (lines A12, A10, A15, and A34) were measured using semiquantitative RT-PCR analysis with ACT2 as an internal standard. B, Sizes of 30-d-old transgenic plants: The lengths of shoots of the transgenic plants became dwarfed as the expression level of FAB1A increased. C, Expression levels of the four transgenic lines expressing FAB1B (lines B11, B19, B80, and B82) were measured using semiquantitative RT-PCR. D, Viability of pollen from these transgenic plants was measured by counting the FDA-stained pollen grains. The pollen grains of four lines and the wild type were stained with FDA. Grains exhibiting FDA fluorescence were counted (number of grains counted: wild type, n = 152; line B19, n = 233; line B11, n = 385; line B80, n = 245; line B82, n = 225). Asterisks denote statistically significant differences in the viability of pollen of each line compared with wild type (*P < 0.001; Student’s t test). [See online article for color version of this figure.]

Reduction of FAB1A/B and overexpression of FAB1A or FAB1B cause acidification defect of central vacuoles of the root epidermal cells. Root epidermal cells of 5-d-old seedlings of FAB1A/B-amiRNA (A and B) or iFAB1A-OX (C and D) and iFAB1B-OX (E and F) lines were stained with acridine orange. Fluorescence was observed using confocal microscopy. The root epidermal cells in which reduction of FAB1A/B expression (B), overexpression of FAB1A (D), and overexpression of FAB1B (F) were induced in the presence of estradiol. Although the central vacuoles were fully acidificated in the root epidermal cells of noninduced FAB1A/B-amiRNA line (A), iFAB1A-OX line (C), and iFAB1B-OX line (E), no acidification inside of the central vacuole was observed in each line of cells (B, D, and F). Bar = 50 μm. [See online article for color version of this figure.]

Transgenic plants expressing FAB1A represents abnormal floral organ phenotypes. Overexpression of FAB1A caused abnormal flower types, including ovule-like structures appearing inside of a curled sepal (A), sepals with a carpel-like structure (B), ovule-like structures in a curled leaf (C), a stamen fused to sepals (D), papilla that emerged on the stamen tip (E), and three flowers branched from a single place, as in the terminal flower phenotype (F). [See online article for color version of this figure.]